The present invention relates to circuit breakers and more particularly to draw-out circuit breakers and is an improvement of the racking mechanism for the draw-out circuit breaker as shown in U.S. Pat. No. 4,101,744 issued July 18, 1978, and assigned to the assignee of the present invention.
In the racking mechanism structure therein shown a racking shaft extending longitudinally through the circuit breaker was rotated after the circuit breaker was initially inserted into the cubicle in order to draw the circuit breaker fully into the cubicle. Also, the racking mechanism was rotated in an opposite direction in order to cause the circuit breaker to be withdrawn from the cubicle.
The racking mechanism is stationary but rotation thereof operates a travelling nut which moves along a threaded portion of the racking shaft to operate a lever which results in pulling the circuit breaker into the cubicle; and rotation of the racking shaft in an opposite direction forces the circuit breaker toward the front of the cubicle.
The present invention simplifies the operation by providing a simplified link or pair of links carrying a pin. The action of the links is controlled as a result of the rotation of the horizontal racking shaft. The pin carried by the links is adapted to engage a hook on the cradle or support for the circuit breaker within the cubicle. The hook since it is attached to the cradle is a stationary structure. When the pin carried by the links engages an appropriate portion of the hook, rotation of the racking shaft in an appropriate direction will cause the pin to drop into a notch in the hook. The links and a travelling nut, engaged at their opposite end, are now held stationary and the rotation of the racking shaft moves it with respect to the nut. Since a collar on the racking shaft bears against the circuit breaker housing, the entire circuit breaker moves into the cubicle.
In reverse operation, when the circuit breaker is to be withdrawn from the cubicle, rotation of the racking shaft in an opposite direction will cause the racking shaft to travel in a direction toward the front of the compartment thereby causing the circuit breaker to be pushed out of the cubicle; after the links have travelled a predetermined distance continued rotation of the racking shaft will cause the links to rise and the pin to disengage from the hook so that the circuit breaker may be withdrawn from the cubicle.
The circuit breaker links and pin are so arranged that if the racking shaft has been rotated to a position where the links and pin are in a down position while the circuit breaker is withdrawn from the cubicle, then the insertion of the circuit breaker into the cubicle will cause the pin to engage an obstruction actually constituting an extension of the hook. The circuit breaker cannot be moved into the cubicle until the racking shaft has been rotated into the correct position for insertion with the links and pin raised whereupon the racking shaft may be properly rotated to draw the circuit breaker into the cubicle.
The primary object of the present invention, therefore, is the provision of a simplified racking mechanism and particularly a simplified means of interconnecting the circuit breaker racking mechanism with the cradle in the cubicle so that the circuit breaker may readily be driven into the cubicle and readily moved out of the cubicle with appropriate controls and interlocks so that the circuit breaker cannot be inserted into the cubicle unless the racking mechanism is in a racked out position for the circuit breaker so that the racking mechanism may properly engage the hook on the cradle or stationary structure within the cubicle which is designed to support the circuit breaker.